2.81 Phototropism

- Phototropism. Photo = Light. Tropism = Growth in response to light. "Positive" shows towards the light
- If light comes from all directions the stem will grow forwards and upwards
- If light comes from lateral light source the stem will start growing towards the light (bends to face) 
- Light on one side, causes movement of opposite side of a compound, Auxin (plant hormone). 
- Auxin cause more growth on the opposite then on the light side, causing it to bend